In order to solve the problems of difficult test, high cost and long cycle in the development of large-scale airborne negative pressure isolation system, the simulation analysis of negative pressure response characteristics is carried out around various aviation conditions such as aircraft ascending, leveling and descending, especially rapid decompression, based on the computational fluid dynamics (CFD) method. The results showed that the isolation cabin could achieve –50 Pa pressure difference environment and form a certain pressure gradient. The exhaust air volume reached the maximum value in the early stage of the aircraft’s ascent, and gradually decreased with the increase of altitude until it was level flying. In the process of aircraft descent, the exhaust fan could theoretically maintain a pressure difference far below –50 Pa without working; Under the special condition of rapid pressure loss, it was difficult to deal with the rapid change of low pressure only by the exhaust fan, so it was necessary to design safety valve and other anti-leakage measures in the isolation cabin structure. Therefore, the initial stage of aircraft ascent is the key stage for the adjustment and control of the negative pressure isolation system. By controlling the exhaust air volume and adjusting parameters, it can adapt to the change of low pressure under normal flight conditions, form a relatively stable negative pressure environment, and meet the needs of biological control, isolation and transport.
ObjectiveTo investigate the pathogenesis and treatment of obstructive sleep apnea hypopnea syndrome (OSAHS) by detecting the changes of serum interleukin-23 (IL-23) and C-reactive protein (CRP) levels of the OSAHS patients before and after treatment with continuous positive airway pressure (CPAP).MethodsFifty-eight patients with moderate to severe OSAHS diagnosed by polysomnography were recruited as an experimental group, 57 out-patient healthy subjects with matched age, sex and body mass index of the experimental group were enrolled as a control group. The serum concentrations of IL-23 and CRP in the experimental group were detected and compared before and after CPAP application for 3 months. The serum concentrations of IL-23 and CRP in the control group were also measured.ResultsThe serum levels of IL-23 and CRP in the OSAHS patients were significantly higher than those in the normal control subjects (P<0.05). The serum levels of IL-23 and CRP in the OSAHS patients after CPAP treatment were significantly lower than those before CPAP treatment (P<0.05). The serum concentrations of IL-23 and CRP were positively correlated with apnea hypopnea index (r=0.756, r=0.345, P<0.05, respectively), and negatively correlated with mean oxygen saturation (r=–0.715, r=–0.334, P<0.05, respectively).ConclusionsThe serum levels of IL-23 and CRP are positively correlated with the severity of OSAHS. After CPAP treatment, the levels of IL-23 and CRP decrease, which indicates that CPAP treatment may reduce the inflammatory reaction and correct anoxia of OSAHS patients.
ObjectiveTo systematically review the relationship between frailty and risk of orthostatic hypotension.MethodsPubMed, EMbase, Web of Science, CNKI, CBM, VIP and WanFang Data databases were electronically searched to collect studies on the association between frailty and orthostatic hypotension from inception to July 7th, 2020. Two reviewers independently screened literature, extracted data and assessed risk of bias of included studies. Meta-analysis was then performed by RevMan 5.3 software.ResultsFive cross-sectional studies involving 8 671 patients were included. The results of meta-analysis showed that prefrailty (OR=1.04, 95%CI 0.99 to 1.09, P=0.11) and frailty (OR=1.02, 95%CI=0.92 to 1.13, P=0.70) were not associated with orthostatic hypotension. The results of subgroup analysis showed that differences of sample size (<500 or ≥500), using different frailty assessment tools (Fried scale, clinical frailty scale, and frailty index), different regions (Europe, Asia, and America) and different sources of studied subjects (hospitals and communities), the risk of orthostatic hypotension were not increased with frailty.ConclusionsCurrent evidence shows that frailty does not increase the risk of orthostatic hypotension. Due to limited quality and quantity of included studies, the above conclusions are needed to be validated by more high-quality studies.
ObjectiveTo evaluate the effects of home mechanical ventilation (HMV) for stable chronic obstructive pulmonary disease (COPD) patients with respiratory failure in Tongzhou district of Beijing city. MethodsTwenty stable COPD patients with respiratory failure were included in the study.During the one-year follow-up period,4 patients died and 1 withdrew and 15 patients finished the follow-up.The patients was followed up by telephone each month and guided in drug administration,HMV,and rehabilitation therapy.At the beginning of the study and one year later,the patients were interviewed and accessed on the general data,nutritional status,COPD assessment test (CAT),Borg dyspnea and respiratory fatigue score,Hamilton depression scale,Hamilton anxiety scale,and arterial blood gas analysis. ResultsAt the end of one-year follow-up,nutrition index,CAT,Borg dyspnea and respiratory fatigue score,Hamilton depression scale,Hamilton anxiety scale,pH,and PaO2 did not change significantly (P>0.05),while PaCO2 decreased significantly compared with those at the beginning of the study (P<0.05).Compared with the past year,the times of hospitalization due to acute exacerbation of COPD was significantly reduced during the follow-up year (P<0.05). ConclusionHMV can ameliorate carbon dioxide retention and reduce times of hospitalization due to acute exacerbation of COPD for COPD patients with respiratory failure.
Corticosteroids, anti-vascular endothelial growth factor, antibiotics and antiviral were the main 4 classes of drugs for intravitreal injection. Depending on the class and volume of medication, age and gender of patients, ocular axial lengths or vitreous humour reflux, intraocular pressure (IOP) can be elevated transiently or persistently after intravitreal injection. Transient IOP elevation occurred in 2 weeks after intravitreal injection, and can be reduced to normal level for most patients. Only a small portion of such patients have very high IOP and need intervention measures such as anterior chamber puncture or lowering intraocular pressure by drugs. Long term IOP elevation is refers to persistent IOP increase after 2 weeks after intravitreal injection, and cause optic nerve irreversible damage and decline in the visual function of patients. Thus drug or surgical intervention need to be considered for those patients with high and long period of elevated IOP. Large-scale multicenter clinical trials need to be performed to evaluate the roles of the drug and patients factors for IOP of post-intravitreal injection, and to determine if it is necessary and how to use methods reducing IOP before intravitreal injection.
Objective To review randomized controlled trials of blood pressure (BP) lowering therapy on stroke prevention to provide evidence for clinical practice. Methods We searched Medline (1966-2003.6) and the large-sample randomized controlled trials on BP lowering regimen in patients with stroke history were reviewed. Endpoints included the ocurrance of stroke, coronary heart disease and mortality. Results Three trials of PATS, PROGRESS and HOPE were analysed. The review showed that stroke recurrent risk was reduced by 28%, CHD risk decreased by 15% and total mortality risk reduced by 11% in BP lowering treatment group compared with placebo control group. Stroke risk was reduced not only in hypertensive patients with previous cerebrovascular diseases but also in non-hypertensive patients. Conclusions BP lowering therapy is beneficial for the secondary prevention of stroke.
Objectives To systematically review the preventive effects of different pressure relief devices. Methods Databases including PubMed, The Cochrane Library, Web of Science, EMbase, CBM, CNKI, VIP and WanFang Data were searched to collect randomized control trials (RCTs) on the preventive effects of pressure relief devices for the surgical pressure sore from inception to December 2017. Two reviewers independently screened literature, extracted data and assessed risk of bias of included studies. Network meta-analysis was then performed using gemtc package of R 3.5.0 software, Stata 13.0 and JAGS 3.4.0 software. Results A total of 20 RCTs involving 4 183 patients were included. The network meta-analysis showed that micropulse dynamic pad was superior to standard pad. The gel pad was superior to sponge pad. The standard pad and cotton gauze pad. The foam dressing was superior to gel pad. All of the differences were statistically significant. The results of the ranking probability plot suggested foam dressing as an optimal resolution for preventing surgical pressure sore. Conclusions According to the network meta-analysis and rankings, foam dressing is superior to other decompression devices in preventing surgical pressure sores.
ObjectiveTo explore the effect of different ventilation modes on pulmonary complications (PCs) after laparoscopic weight loss surgery in obese patients. MethodsThe obese patients who underwent laparoscopic weight loss surgery in the Xiaolan People’s Hospital of Zhongshan from January 2019 to June 2023 were retrospectively collected, then were assigned into pressure-controlled ventilation-volume guaranteed (PCV-VG) group and volume controlled ventilation (VCV) group according to the different ventilation modes during anesthesia. The clinicopathologic data of the patients between the PCV-VG group and VCV group were compared. The occurrence of postoperative PCs was understood and the risk factors affecting the postoperative PCs for the obese patients underwent laparoscopic weight loss surgery were analyzed by multivariate logistic regression analysis. ResultsA total of 294 obese patients who underwent laparoscopic weight loss surgery were enrolled, with 138 males and 156 females; Body mass index (BMI) was 30–55 kg/m2, (42.40±4.87) kg/m2. The postoperative PCs occurred in 63 cases (21.4%). There were 160 cases in the PCV-VG group and 134 cases in the VCV group. The anesthesia time, tidal volume at 5 min after tracheal intubation, peak inspiratory pressure and driving pressure at 5 min after tracheal intubation, 60 min after establishing pneumoperitoneum, and the end of surgery, as well as incidence of postoperative PCs in the PCV-VG group were all less or lower than those in the VCV group (P<0.05). The indicators with statistical significance by univariate analysis in combination with significant clinical indicators were enrolled in the multivariate logistic regression model, such as the smoking history, American Society of Anesthesiologists classification, hypertension, BMI, operation time, forced expiratory volume in 1 second (FEV1), FEV1/forced vital capacity, and intraoperative ventilation mode. It was found that the factors had no collinearity (tolerance>0.1, and variance inflation factor<10). The results of the multivariate logistic regression analysis showed that the patients with higher BMI and intraoperative VCV mode increased the probability of postoperative PCs (P<0.05). ConclusionsFrom the preliminary results of this study, for the obese patients underwent laparoscopic weight loss surgery, the choice of ventilation mode is closely related to the risk of developing postoperative PCs. In clinical practice, it is particularly important to pay attention to the risk of postoperative PCs for the patients with higher degree obesity.
Objective Sedation and/or analgesia is often applied during noninvasive positive pressure ventilation (NIPPV) to make patients comfortable, and thus improve the synchronization between patients and ventilator. Nevertheless, the effect of sedation and/or analgesia on the clinical outcome of the patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) after extubation remains controversial. Methods A retrospective study was conducted on patients with AECOPD who received NIPPV after extubation in seven intensive care units in West China Hospital, Sichuan University between December 2013 and December 2017 . A logistic regression model was used to analyze the association between the use of sedation and/or analgesia and clinical outcomes including rate of NIPPV failure (defined as the need for reintubation and mechanical ventilation), hospital mortality, and length of intensive care unit stay after extubation. Results A total of 193 patients were included in the analysis, and 62 cases of these patients received sedation and/or analgesia during NIPPV. The usage of sedation and/or analgesia could result in failure of NIPPV (adjusted odd ratio [OR] 0.10, 95% confidence interval [CI] 0.02 - 0.52, P=0.006) and death (adjusted OR=0.13, 95%CI 0.04 - 0.42, P=0.001). Additionally, intensive care unit stay after extubation was longer in the patients who did not receive sedation and/or analgesia than those who did (11.02 d vs. 6.10 d, P< 0.01). Conclusion The usage of sedation and/or analgesia during NIPPV can decrease both the rate of NIPPV failure and hospital mortality in AECOPD patients after extubation.
This study aims to explore the intraventricular pressure difference (IVPD) within left ventricle in patients with paroxysmal atrial fibrillation (PAF) by using the relative pressure imaging (RPI) of vector flow mapping (VFM). Twenty patients with paroxysmal atrial fibrillation (PAF) and thirty control subjects were enrolled in the study. Systolic and diastolic IVPD derived from VFM within left ventricle and conventional echocardiographic parameters were analyzed. It was found that the B-A IVPD of left ventricle in PAF patients showed the same pattern as controls—single peak and single valley during systole and double peaks and double valleys during diastole. Basal IVPD was the main component of base to apex IVPD (B-A IVPD). The isovolumetric systolic IVPD was associated with early systolic IVPD, early systolic IVPD was associated with late systolic IVPD, and late systolic IVPD was associated with isovolumic diastolic IVPD (all P < 0.05). The B-A IVPD and basal IVPD during isovolumetric systole, early systole, late systole and isovolumetric diastole in PAF patients significantly decreased (all P < 0.05). The study shows that the B-A IVPD pattern of the PAF group is the same as controls, but systolic B-A IVPD and basal IVPD are significantly reduced in PAF patients. VFM-derived RPI can evaluate left ventricular IVPD in PAF patients, providing a visually quantitative method for evaluating left ventricular hemodynamic mechanics in the patients with PAF.